Galvanized steel has been proposed to be used in the automotive industry to provide improved corrosion resistance for specific components. Unfortunately, the gloss of painted zinc surfaces and mild steel are difficult to match.
It has, therefore, been proposed to provide the zinc coating on the intended inner surface only of the steel strip, thereby allowing painting of the exterior steel metal surface in conventional manner.
Various suggestions have been made for producing a selectively galvanized product, but none to date has been entirely commercially satisfactory from an economic standpoint. Prior art suggestions have included electrolytic zinc deposition on one side only of the steel strip, melt coating of zinc on one side only of the steel strip using sophisticated mechanical coating apparatus, hot-dip galvanizing the steel strip on both sides in conventional manner and subsequently removing the coating from one side of the strip using acid, and providing some sort of barrier layer on the side of the sheet on which zinc is not desired to prevent wetting of that side during the galvanizing of the steel strip, the barrier layer subsequently being removed or left in contact with the steel strip, depending on the coating concerned.